CHARACTERIZATION OF THE PEPTIDE-N-4-(N-ACETYLGLUCOSAMINYL) ASPARAGINEAMIDASE (PNGASE SE) FROM SILENE ALBA CELLS

The peptide-N-4-(N-acetylglucosaminyl) asparagine amidase (PNGase Se) earlier described [Lhernould S,, Karamanos Y., Bourgerie S., Strecker G., Julien R., Morvan H. (1992) Glycoconjugate J 9:191-97] was partial ly purified from cultured Silene alba cells using affinity chromatogra phy. The enzyme is active between pH 3.0 and 6.5, and is stable in the presence of moderate concentrations of several other protein unfoldin g chemicals, but is readily inactivated by SDS. Although the enzyme cl eaves the carbohydrate from a variety of animal and plant glycopeptide s, it does not hydrolyse the carbohydrate from most of the correspondi ng unfolded glycoproteins in otherwise comparable conditions, The subs trate specificity of this plant PNGase supports the hypothesis that th is enzyme could be at the origin of the production of 'unconjugated N- glycans' in a suspension medium of cultured Silene alba cells.